A present invention relates to a process for producing a lead-acid battery and more particularly, a process for producing a lead-acid battery related to welding of terminal portions of the battery, and a jig for producing the same.
It is a conventional practice either to produce a lead-acid battery of a so-called bushing terminal type in which a lead bushing also serves as a terminal, by inserting an upper portion of a pole protruding upwards from a cell chamber within a battery container of an assembled lead-acid battery through an insertion hole in a lead bushing cast in a lid made of a synthetic resin by a cast molding process, and welding the pole inserted and the lead bushing around an outer periphery of the pole to each other, or to produce a lead-acid battery of a type having a terminal member led out sideways by mounting a separately fabricated terminal on an outer peripheral surface of a lead bushing, and welding the bushing and the terminal to each other using a burner.
In this case, at the time of welding using the burner, as mentioned above, in order to previously prevent that the lid would be deformed due to a welding heat, whereby an air-tightness failure would occur between the lid and the lead bushing integrally cast in the lid, it has preferably practiced in general to carry out the burner welding in such a state that an annular mold of a jacket type for passing cooling water therethrough is disposed in contact with around the peripheral surface of the lead bushing or the peripheral surface of the terminal mounted on the bushing.
More particularly, in the case of producing the lead-acid battery of a bushing terminal type as described above, it has been conventional to weld terminal portions to be welded of the lead-acid battery, i.e., mutually abutted or adjacent peripheral portions of the lead bushing integrally cast in a lid made of a synthetic resin by an insertion molding and a pole of a battery body inserted through a cylindrical hole in the lead bushing to each other by a burner flame.
In the case of welding of the pole and the lead bushing using the burner, however, if the height from the surface of the lid to an upper end surface of the lead bushing is not more than 8 xe2x96xa1 10 mm, in other words, is less than 8 xe2x96xa1 10 mm, it is not avoidable that the lid is deformed due to the heat generated during the burner-welding, even if the above-mentioned cooling means is used, an air-tightness failure is occurred between the lid and the lead bushing formed in the lid. Therefore, it is required that the upper end of the lead bushing protrudes more than 8 xe2x96xa1 10 mm from the surface of the lid, and hence, such a corresponding height-wise space enough to accommodate the lead bushing terminal is required above the upper surface of the lid. On the other hand, it is desirable to produce a lead-acid battery of the type leading out the terminal sideways which is capable of lowering a height-wise space above the upper surface of the lid. However, in the burner-welding of a base portion of the lead bushing and a plate-shaped terminal having a thickness of several mm, fitted thereon the distance between the portion of the terminal to be welded and the surface of the lid is only several mm, so that an air-tightness failure is often generated between the lid and the lead bushing cast in the lid due to the thermal deformation of the lid caused by the burner-welding, to result in many manufacture losses.
Therefore, it is desired to remove such inconveniences and develop a process capable of producing a lead-acid battery, wherein welding of the required portions can be achieved smoothly without any manufacture loss.
When welding of the foregoing terminal portions is carried out using a burner flame, the lid made of a synthetic resin around the terminal portion is softened by heat of the burner flame to create a gap between the lid and the bushing, thereby bringing about an air-tightness failure. In addition, it is difficult to make a depth of penetration of the welded portions uniform and further, the appearance shape of the welded terminal portion is collapsed and hence, it is difficult to make a welded terminal of a definite shape.
Accordingly, it is desired to remove such inconveniences and develop a process for producing a lead-acid battery by such a process for welding of the terminal portions that is capable of welding the terminal portions to each other stably and satisfactorily without any manufacture loss.
It is an object of the present invention to provide a process for producing a lead-acid battery which has removed the problems associated with the prior arts, and the present invention is characterized in that a lead bushing integrally cast in a lid of an assembled lead-acid battery and a pole inserted through the lead bushing are welded together by a laser welding.
Further, a process for producing a lead-acid battery according to the present invention, is characterized in that welding of a lead bushing integrally cast in a lid of an assembled lead-acid battery and a pole inserted through the lead bushing and welding of the lead bushing and a tab terminal member fitly mounted on in the lead bushing are carried by a laser welding.
Further, in the process for producing the lead-acid battery according to the present invention, it is characterized in that at the time of the laser welding a laser beam of a low output is applied and thereafter a laser beam of a high output is applied.
Further, in the process for producing the lead-acid battery according to the present invention, it is characterized in that the laser welding is of a pulsed type.
Further, in the process for producing the lead-acid battery according to the present invention, it is characterized in that the lap density of beads in the laser welding of the pulsed type is in a range of 6 xe2x96xa1 12 points per mm.
Further, it is an object of the present invention to provide a process for the laser welding of the terminal portions of the lead acid battery for preventing a laser beam from intercepting by fumes generated at the time of application thereof in the laser welding in the process for producing the above-mentioned lead-acid battery, to make it possible to carry out the welding at a high efficiency and stably and sufficiently, and it is characterized in that when the laser-welding is carried out by applying the laser to terminal portions to be welded of the lead-acid battery, there is used such a process for laser-welding of the terminal portions that the terminal portions are surrounded by a lower cylindrical end portion of a cylindrical shield, and, in this state, fumes generated at the time of the laser-welding are sucked to be exhausted to the outside of the cylindrical shield through an exhaust port in the cylindrical shield.
Further, it is an object of the present invention to provide a process for the laser welding of the terminal portions which is capable of carrying out the welding by application of the laser beam accurately and at a good efficiency when the above-mentioned process for laser welding is used in the above-mentioned process for producing the lead-acid battery, and it is characterized in that a discharge opening is provided in the cylindrical shield, and oxygen or air is supplied through the discharge opening to the portions to be welded.
Further, it is an object of the present invention to provide a process for laser welding for carrying out the laser welding more accurately and at a better efficiency when the above-mentioned process for laser welding is used in the above-mentioned process for producing the lead-acid battery, and it is characterized in that a shroud ring having the plural of communication openings made circumferentially in its peripheral wall is installed in the cylindrical shield with an annular space left between the shroud ring and the inner peripheral wall surface of the cylindrical shield so that fumes generated in the shroud ring may be sucked to be exhausted out of the cylindrical shield through the communication holes of the shroud ring, the annular space surrounding thereof and the exhaust port, together with a shielding fluid flowed through the discharge opening into the cylindrical shield.
Further, the present invention, which is capable of carrying out the laser welding at a better efficiency while removing the fumes at a good efficiency by the laser welding when the above-mentioned laser welding is used in the above-mentioned process for producing the lead-acid battery, and it is characterized in that the plural communication bores made at regular intervals in the shroud ring are formed into those which are open in a circumferentially tangent direction of the ring, whereby an eddy flow is occurred to the fumes generated inside the shroud ring and is sucked to be exhausted.
Further, it is an object of the present invention to provide a laser welding jig which is suitable for carrying out the above-mentioned process for producing the lead-acid battery, and it is characterized in that an opening of the upper surface of a cylindrical body made of a metal having a good heat conductivity is closed by a light-transmission plate and a lower cylindrical portion thereof is adapted to be fitted on the outer peripheral surface of the terminal portions of a lead-acid battery, so that a cylindrical shield is formed, and the cylindrical shield is provided with the plural discharge openings for a shield fluid disposed circumferentially at the lower portion thereof, and a shroud ring provided with the plural communication openings disposed at regular intervals circumferentially at a position which is above the discharge openings is so installed in the cylindrical shield as to leave an annular space between the shroud ring and the inner surface of a peripheral wall of the cylindrical shield, and the cylindrical shield is provided with an exhaust port which communicates with the annular space.
The disclosure of other characteristics of a process for producing a lead-acid battery and a welding jig used for the same according to the invention will be made clear in detail hereinafter.